The demand for high magnification, high performance, and compactness of the lens system used in a lens shutter camera has been increasing steadily over recent years. In response to these demands, extensive testing has been performed on the use of aspheric surfaces, the use of unique glass material, and in shutter placement.
An example of this type of zoom lens is a three-group zoom lens disclosed in the Japanese Laid-Open Patent Publication No. 5-113539. This zoom lens is composed of three lens groups having, in order from the photographic object side, positive, positive, and negative refractive power, and achieves a high variable power ratio of above 2.5, thereby making possible a reduction in the total length of the zoom lens.
However, with the prior art zoom lens described above, the curvature of field and distortion when in the maximum wide-angle state leave much room for improvement.